The invention relates to the use of metal silicate, particularly a synthetic mica montmorillonite (SMM), as catalyst in the catalytic conversion of hydrocarbons in the presence of hydrogen.
It is known to use metal silicates as catalysts for hydrocarbon conversions, such as cracking and isomerizing in the presence or absence of hydrogen. U.S. Pat. No. 4,022,684 describes an HF-treatment of a Pd-Ni SMM catalyst which reduces its isomerization activity.
It is known to use metal silicates as catalysts for hydrocarbon conversions, such as cracking and isomerizing in the presence or absence of hydrogen.
It is further known, that when subjected to a treatment with hydrogen fluoride the catalytic activity of certain metal silicates in hydroisomerization reactions is decreased.
It has now been found that the catalytic activity of the metal SMM silicates is dependent on the way in which they have been prepared; in particular it has been found that a treatment with one or more compounds comprising releasable active halogen other than fluorine, carried out during the preparation of certain metal silicates is highly effective. For instance, the reaction rate achieved in the catalytic hydroisomerization of unbranched paraffins is considerably higher when using certain metal silicates which have been treated with hydrochloric acid during their preparation than when using the same metal silicates which have not been treated with hydrochloric acid. This was found to be particularly so in the case of at least partly crystalline metal silicates having a crystal lattice substantially consisting of a triplex layer structure containing in the central layer octahedrally coordinated aluminum or at least part of the octahedrally coordinated aluminum replaced by one or more metals from Group VIII of the Periodic Table of Elements, and in the two outer layers tetrahedrally coordinated silicon or at least part of the tetrahedrally coordinated silicon replaced by aluminum.